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mysql_field_flagsGet the flags associated with the specified field in a result


Questa enstensione deprecata da PHP 5.5.0, e sarà rimossa in futuro. Al suo posto, usare l'estensione MySQLi o PDO_MySQL. Vedere anche la guida MySQL: scelta dell'API e le FAQ relative per ulteriori informazioni. Le alternative a questa funzione includono:


mysql_field_flags(resource $result, int $field_offset): string|false

mysql_field_flags() returns the field flags of the specified field. The flags are reported as a single word per flag separated by a single space, so that you can split the returned value using explode().

Elenco dei parametri


The risultato resource che che viene calcolato. Questo risultato deriva dal una chiamata a mysql_query().


L'offset numerico dei campi. field_offset inizia da 0. Se field_offset non esiste, viene generato un errore di livello E_WARNING.

Valori restituiti

Returns a string of flags associated with the result o false in caso di fallimento.

The following flags are reported, if your version of MySQL is current enough to support them: "not_null", "primary_key", "unique_key", "multiple_key", "blob", "unsigned", "zerofill", "binary", "enum", "auto_increment" and "timestamp".


Example #1 A mysql_field_flags() example

= mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!
$result) {
'Could not run query: ' . mysql_error();
$flags = mysql_field_flags($result, 0);

print_r(explode(' ', $flags));

Il precedente esempio visualizzerà qualcosa simile a:

not_null primary_key auto_increment
    [0] => not_null
    [1] => primary_key
    [2] => auto_increment



Per la compatibilità all'indietro, i seguenti sinonimi (deprecati) possono essere utilizzati: mysql_fieldflags()

Vedere anche:

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User Contributed Notes 10 notes

cufarley at nirvanet dot net
22 years ago
Using the "DESC TableName" command may also do the trick and is a bit shorter.
amir at scrounch dot com
20 years ago
returns primary keys of a table using 'show keys'
although it is possible to use desc, show keys offers possible enhancements such a getting sequence in index along with it

function getPrimaryKeyOf($table, $link) {
$pk = Array();

$sql = 'SHOW KEYS FROM `'.$table.'`';
$res = mysql_query($table, $link) or die(mysql_error());
while ($row = mysql_fetch_assoc($res)) {
if ($row['Key_name']=='PRIMARY')
array_push($pk, $row['Column_name']);
return $pk;
play at arcadevillage dot com
14 years ago
To really backup the database values, I made a little changement :

My code really looks like bomas 's code, but there is an important diffence :

= mysql_num_fields($req_table);
while (
$ligne = mysql_fetch_array($req_table))
$insertions = "INSERT INTO $table VALUES(";
for (
$i=0; $i<$nbc; $i++)
if (
$i > 0 ) $insertions .= ", ";
if ( !isset(
$insertions .= "NULL";
$insertions .= "'" . mysql_real_escape_string($ligne[$i]). "'";
$insertions .= ");";
$dumpsql[] = $insertions;

$dumpslq is the variable where I put the insertion orders before writting them in a text file.

Before, I test that the values if not NULL into the field because it is the only way to make the difference, for example for string text fields, between NULL values and empty strings.

If you don't make this test, you should find empty string instead of NULL values when you do the backup.
pike-php at kw dot nl
18 years ago
ok, sorry for the code bloat :) but this is how I
get the full power of mysql's DESCRIBE table statement, in
an associative array, including defaults, enum values, float radix et all.

it assumes mysql returns the type as
"type[(arg[,arg..])] [ add]"
"float(20,6) unsigned"


function getFields($tablename) {

$fields = array();
$fullmatch = "/^([^(]+)(\([^)]+\))?(\s(.+))?$/";
$charlistmatch = "/,?'([^']*)'/";
$numlistmatch = "/,?(\d+)/";

$fieldsquery .= "DESCRIBE $tablename";
$result_fieldsquery = mysql_query($fieldsquery) or die(mysql_error());
while ($row_fieldsquery = mysql_fetch_assoc($result_fieldsquery)) {

$name = $row_fieldsquery['Field'];
$fields[$name] = array();
$fields[$name]["type"] = "";
$fields[$name]["args"] = array();
$fields[$name]["add"] = "";
$fields[$name]["null"] = $row_fieldsquery['Null'];
$fields[$name]["key"] = $row_fieldsquery['Key'];
$fields[$name]["default"] = $row_fieldsquery['Default'];
$fields[$name]["extra"] = $row_fieldsquery['Extra'];

$fulltype = $row_fieldsquery['Type'];
$typeregs = array();

if (preg_match($fullmatch, $fulltype, $typeregs)) {
$fields[$name]["type"] = $typeregs[1];
if ($typeregs[4]) $fields[$name]["add"] = $typeregs[4];
$fullargs = $typeregs[2];
$argsreg = array();
if (preg_match_all($charlistmatch, $fullargs, $argsreg)) {
$fields[$name]["args"] = $argsreg[1];
} else {
$argsreg = array();
if (preg_match_all($numlistmatch, $fullargs, $argsreg)) {
$fields[$name]["args"] = $argsreg[1];
} else die("cant parse type args: $fullargs");
} else die("cant parse type: $fulltype");

return $fields;


simone dot t at betisgroup dot com
21 years ago
Another examples :


function field_keys($host, $user, $password, $database, $field ) {
$db_link = mysql_connect($host, $user, $password) or die ("error connect");
$query="DESC $field";
while ($row=mysql_fetch_array($results)) {
if ($row[Key]=="PRI") {
return $array_keys;


//Example of Main...
$tmp = field_keys("localhost", "myuser", "mypassword", "mydb", "field_name" );

// ...loop through array...
foreach ( $tmp as $array_tmp){
print "<br>";
print $array_tmp;
print "<br>";
jakemsr at jakemsr dot com
21 years ago
I didn't find anything to get the valid values for
ENUM or SET column types, so I came up with the

function mysql_enum_values($table, $field)
$sql = "SHOW COLUMNS FROM $table LIKE '$field'";
$sql_res = mysql_query($sql)
or die("Could not query:\n$sql");
$row = mysql_fetch_assoc($sql_res);
preg_replace("/.*\('(.*)'\)/", "\\1",
bomas at cities-of-faith dot com
18 years ago
well, to make a complete backup of your database, i suggest this code:

//open database here
$tab_status = mysql_query("SHOW TABLE STATUS");
while($all = mysql_fetch_assoc($tab_status)):
$tbl_stat[$all[Name]] = $all[Auto_increment];
$tables = mysql_list_tables('cofadmin');
while($tabs = mysql_fetch_row($tables)):
$backup .= "--\n--Tabel structuur voor `$tabs[0]`\n--\n\nDROP IF EXISTS TABLE `$tabs[0]`\nCREATE TABLE IF NOT EXISTS `$tabs[0]` (&nbsp;";
$res = mysql_query("SHOW CREATE TABLE $tabs[0]");
while($all = mysql_fetch_assoc($res)):
$str = str_replace("CREATE TABLE `$tabs[0]` (", "", $all['Create Table']);
$str = str_replace(",", ",&nbsp;", $str);
$str2 = str_replace("`) ) TYPE=MyISAM ", "`)\n ) TYPE=MyISAM ", $str);
$backup .= $str2." AUTO_INCREMENT=".$tbl_stat[$tabs[0]].";\n\n";
$backup .= "--\n--Gegevens worden uitgevoerd voor tabel `$tabs[0]`\n--\n\n";
$data = mysql_query("SELECT * FROM $tabs[0]");
while($dt = mysql_fetch_row($data)):
$backup .= "INSERT INTO `$tabs[0]` VALUES('$dt[0]'";
for($i=1; $i<sizeof($dt); $i++):
$backup .= ", '$dt[$i]'";
$backup .= ");\n";
$backup .= "\n-- --------------------------------------------------------\n\n";
echo $backup;

this displayes your data the same way as phpmyadmin does.

hope it helps some of you guys
justin DOT flavin AT ntlworld DOT com
21 years ago
Sometimes, when writing a generic function or class, you want your script to be able to determine what the primary key of a table is.
/* usual MySQL stuff */
$query="DESC UsersTable";

while ($row=mysql_fetch_array($results))
if ($row[Type]="PRI")
print "I found the primary key! <br>";
print $row[Field];
/* drop out , as we've found the key */

..... later on we might have something like

< some sort of loop through records >

print "<a href='View_User_record.php?userkey=$UserKey'> Users Name </a>";

<end loop>

What's also interesting is the useful data you can get from
a DESC query.

The following prints out the array values grabbed by mysql_fetch_array on a DESC query - VERY useful stuff!!!

/* usual MySQL stuff */
$query="DESC UsersTable";

while ($row=mysql_fetch_array($results))
print "<pre>";
print_r ($row);
print "</pre>";
buttrose at unimelb dot edu dot au
19 years ago
This function is essential for writing a generic table editor (ie one that just takes the name of the table and works out what fields it has, types, sizes etc.). Unfortunately, I am using psotgreSQL not mySql. Postgres has field_type and field_size functions but not as far as I can tell an equivalent of the mysql_field_flags() function. Without it, there is no way I can do generic ADDs and INSERTs.

Anyone know a workaround to get this information (eg is the field a primary key? Can it be NULL? Is it auto_increment?) in Postgres?


Rob Buttrose
jurgen at alienguitar dot com
23 years ago
The previous problem to get the default values of a column:
Use the following query and parse the 'Default' column:


or for a single entry:

"SHOW COLUMNS FROM TableName LIKE 'column'"

It will give you also values for Type, Null, Key and Extra (check with mysql program first, so you see what you get ;-)
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